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27 lines
553 B
Ruby
27 lines
553 B
Ruby
module BST
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Node = Struct.new(:value, :parent, :left, :right)
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# Finds the 'next' node (in-order successor) of a given node in a binary search tree,
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# see examples in test/bst_test.rb
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def self.find_next(node)
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return nil if node.nil?
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# find the left most node in the right subtree
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if node.right
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n = node.right
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n = n.left while n.left
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return n
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end
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# otherwise go up until we're on the left side
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n = node
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p = n.parent
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while p && p.left != n
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n = p
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p = p.parent
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end
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p
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end
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end
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